It is well known to provide a vehicle heating, ventilation, and air conditioning (HVAC) system to control an interior temperature and humidity of a vehicle passenger cabin, typically by utilizing pressure differences to transfer heat from low-temperature regions to high-temperature regions of the HVAC system by principles of conduction and convection. Such HVAC systems differ in various aspects of design, fabrication, and operation. However, most vehicle HVAC systems include at least five major components: 1) an evaporator; 2) a compressor; 3) a condenser; 4) a receiver/drier; and 5) an expansion device.
The typical HVAC system is also divided into two pressure regions. The representative HVAC system 100 schematic presented in FIG. 1 includes a high pressure side 102 comprising the condenser 104 and the receiver/drier unit 106, and a low pressure side 108 comprising the evaporator 110. An arbitrary dividing line L between the high pressure region 102 and the low pressure region 108 passes through the compressor 112 and the expansion device 114. Arrows A illustrate the flow of refrigerant through the system 100.
As is also well-known, the evaporator 110 is a heat exchange device that comprises coils for passing refrigerant therethrough to absorb heat from air that is blown over the coils by a fan 111. Refrigerant passes through the evaporator 110 from bottom to top, absorbing heat from the air and boiling the refrigerant to produce low temperature, low pressure vapor. The compressor 112 absorbs the vapor refrigerant via a suction line 116 and superheats it by compression. As refrigerant flows across the compressor 112 it also removes the heat of compression, motor heat, mechanical friction heat, and other heat absorbed in the suction line 116. The compressor 112 also generates a flow of refrigerant in the HVAC system.
The condenser 104 is another heat exchanger comprising coils that cool refrigerant vapor sufficiently to condense it to a liquid, releasing heat from the system. Refrigerant flows through the condenser 104 typically from top to bottom, cooling sufficiently to convert back to a liquid. Heat released during the cooling of the refrigerant is removed by a fan 113. This heat in some HVAC designs is used to assist in warming the vehicle passenger cabin.
The receiver/drier unit 106 filters refrigerant to remove contaminants, and also includes a desiccant to remove excess moisture from the system. The receiver/dryer 106 also stores extra refrigerant during periods of low cooling demand. The expansion device 114 generates a pressure difference causing liquid refrigerant to boil into vapor, that is, by creating a pressure drop by restricting the flow of refrigerant through the HVAC system 100. This slowing of refrigerant flow causes the compressor 112 to partially evacuate one side of the HVAC system 100, creating a low pressure void sometimes called the “suction side” or “low side” of the system.
The typical HVAC system also includes multiple hoses and/or pipes (collectively referred to as “lines”) for moving high and low pressure liquids and vapors between and through the HVAC components as summarized above. These include the suction line 116 as discussed above, and also other high and low pressure lines 118 designed to allow circulation of a variety of fluids at varying temperatures and pressures through the HVAC system 100. It will be appreciated that by the terms “high” and “low” pressure lines, it is meant that the lines are fabricated to withstand varying degrees of temperature and/or pressure imposed by the fluids (liquids, vapors, gases, etc.) passed through and/or generated by the HVAC system 100 as summarized above. Conventionally, high and low pressure lines are separate and separately routed through the HVAC system 100 and/or the vehicle (not shown) underbody area, under-hood region, etc. This imposes engineering challenges in routing the lines, as the separately routed lines require additional packaging space that can be difficult to find in the modern motor vehicle wherein hundreds if not thousands of components must be packaged in the vehicle underbody and under-hood areas.
Moreover, high pressure lines are typically fabricated of more heat/pressure-resistant materials such as metals, including without intending any limitation aluminum and alloys. These high pressure lines are engineered to withstand extremes of internal temperature and pressure imposed by the fluids being transported therethrough. On the other hand, low pressure lines which are not required to transport fluids placed under high temperature and/or high pressure are often for reasons of cost fabricated of less heat/temperature-resistant materials such as plastics. Because the low pressure lines must still be routed through and around the vehicle motor and also vehicle underbody areas which may be generating heat and/or which may be prone to impacts such as from road debris, at least portions of the low pressure lines must often be protected to prevent damage, such as by heat and/or impact-resistant shielding. This further increases cost.
To solve this and other problems, the present disclosure relates at a high level to an HVAC conduit, and to HVAC systems incorporating same. Advantageously, the described conduit includes a more temperature, pressure, and impact-resistant HVAC line nested with a less temperature, pressure, and impact-resistant HVAC line. By such conduits, high and low pressure HVAC lines may be conveniently co-routed in and through vehicle areas such as the underbody area, under-hood region, etc. Moreover, the more temperature, pressure, and impact-resistant HVAC line serves to protect the less temperature, pressure, and impact-resistant HVAC line, thus obviating or reducing the need to provide dedicated shielding for that purpose.